Compare canned and fresh ingredient cost per serving.
Canned and fresh are only comparable once both are reduced to cost per gram of food you actually eat. For a can that means drained weight, not the net weight printed on the label, since a large share of the contents is brine or juice you pour away. For fresh produce it means deducting peel, stalks and cores plus the portion that spoils before you get to it — a real cost that is invisible at the till and typically runs 15 to 30 percent for fresh vegetables. Once both sides are on that basis, canned frequently wins on price while fresh wins on texture and on some heat-sensitive vitamins.
Canned unit cost
Per 100 g = can price / drained grams x 100
Fresh unit cost
Per 100 g = pack price / (pack grams x (1 - waste%)) x 100
Net weight includes the liquid, which can be a third or more of a can of beans or sweetcorn. Comparing a can's net weight against fresh produce flatters the can substantially. Drained weight is usually printed on the label just below net weight.
It depends on the nutrient. Heat processing reduces vitamin C and some B vitamins, but canning locks in others and canned tomatoes actually deliver more available lycopene than raw. Canned produce is also picked at ripeness, whereas fresh may have spent a week in transit losing vitamins.